<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
<style>
    .container{
        width: 200px;
        height: 200px;
        background-color: #888;
        position: relative;
        margin-left: 100px;
    }

    .box{
        width: 100px;
        height: 100px;
        background-color: blueviolet;
        position: absolute;
        left: 50px;
        top: 50px;
    }
</style>

</head>
<body>
    <!-- 对固定定位文件中的温馨提示做的讲解 -->
    <div class="container">
        <div class="box"></div>
    </div>
</body>
</html>